Microdevices are manufactured by depositing and working several layers of materials on a single substrate to produce a large number of individual devices. For example, layers of photoresist, conductive materials, and dielectric materials are deposited, patterned, developed, etched, planarized, and otherwise manipulated to form features in and/or on a substrate. The features are arranged to form integrated circuits, micro-fluidic systems, and other structures.
Wet chemical processes are commonly used to form features on microfeature workpieces. Wet chemical processes are generally performed in wet chemical processing tools that have a plurality of individual processing chambers for cleaning, etching, electrochemically depositing materials, or performing combinations of these processes. FIG. 1 schematically illustrates an integrated tool 10 that can perform one or more wet chemical processes. The tool 10 includes a housing or cabinet 20 having a platform 22, a plurality of wet chemical processing chambers 30 in the cabinet 20, and a transport system 40. The tool 10 also includes lift-rotate units 32 coupled to each processing chamber 30 for loading/unloading the workpieces W. The processing chambers 30 can be rinse/dry chambers, cleaning capsules, etching capsules, electrochemical deposition chambers, or other types of wet chemical processing vessels. The transport system 40 includes a linear track 42 and a robot 44 that moves along the track 42 to transport individual workpieces W within the tool 10. The integrated tool 10 further includes a workpiece storage unit 60 having a plurality of containers 62 for holding workpieces W. In operation, the robot 44 transports workpieces to/from the containers 62 and the processing chambers 30 according to a predetermined workflow within the tool 10.
Automated handling of workpieces is an important aspect in the performance of semiconductor processing tools. As shown in FIG. 1, the robot 44 must accurately transfer and position workpieces at six different processing chambers 30 and two containers 62. The robot 44 moves the workpieces W among the processing chambers 30 and the containers 62 by moving along the track 42, rotating about several pivot points, and raising/lowering the workpiece W in a variety of complex motions.
One challenge of automated handling of workpieces is to properly calibrate the various components of the transport system 40 to move accurately to/from the processing chambers 30 and the containers 62. The transport system 40 is calibrated by “teaching” the robot 44 the specific positions of the chambers 30 and containers 62. Conventional processes for teaching the robot 44 usually involve manually positioning the robot 44 at a desired location with respect to each chamber 30 and each container 62. The encoder value corresponding to the position of the robot at each of these components is recorded and inputted as a program value. In addition to teaching the robot specific locations within the tool, the arms and end-effectors of the robot must be aligned with the reference frame in which the program values for the processing chambers 30 and the containers 62 were recorded. Although manually aligning the components of the robot to the reference frame and manually teaching the robot the location of each processing chamber 30 and container 62 is an accepted process for setting up the transport system 40, it is also extremely time consuming and subject to operator error. For example, it takes approximately 6–8 hours to align the components of a dual end-effector robot to the reference frame and to teach the robot the locations of ten chambers and two containers. Moreover, the quality of each inputted value is subject to operator error because it is often difficult to accurately position the robot in one or more of the chambers 30 or containers 62.
Another challenge of operating integrated wet chemical processing tools is repairing and/or maintaining the processing chambers. In electrochemical deposition chambers, for example, consumable electrodes degrade over time because the reaction between the electrodes and the electrolytic solution decomposes the electrodes. The shape of consumable electrodes accordingly changes causing variations in the electrical field. As a result, consumable electrodes must be replaced periodically to maintain the desired deposition parameters across the workpiece. The electrical contacts that contact the workpiece also may need to be cleaned or replaced periodically. To maintain or repair electrochemical deposition chambers, they are typically removed from the tool 10 and replaced with an extra chamber.
One problem with repairing or maintaining existing wet chemical processing chambers is that the tool must be taken offline for an extended period of time to remove and replace the processing chambers 30 from the tool 10. When the processing chamber 30 is removed from the tool 10, a pre-maintained processing chamber 30 is mounted to the platform 22 at the vacant station, and then the lift-rotate unit 32 is recalibrated to operate with the new processing chamber. The robot 44 is then re-taught to operate with the new position of the lift-rotate unit 32. This is a time-consuming process that increases the downtime for repairing or maintaining processing chambers for the reasons explained above. As a result, when only one processing chamber 30 of the tool 10 does not meet specifications, it is often more efficient to continue operating the tool 10 without stopping to repair the one processing chamber 30 until more processing chambers do not meet the performance specifications. The loss of throughput of a single processing chamber 30, therefore, is not as severe as the loss of throughput caused by taking the tool 10 offline to repair or maintain a single one of the processing chambers 30.
The practice of operating the tool 10 until at least two processing chambers 30 do not meet specifications severely impacts the throughput of the tool 10. For example, if the tool 10 is not repaired or maintained until at least two or three processing chambers 30 are out of specification, then the tool operates at only a fraction of its full capacity for a period of time before it is taken offline for maintenance. This increases the operating costs of the tool 10 because the throughput not only suffers while the tool 10 is offline to replace the wet processing chambers 30 and reteach the robot 44, but the throughput is also reduced while the tool is online because it operates at only a fraction of its full capacity. Moreover, as the feature sizes decrease, the electrochemical deposition chambers 30 must consistently meet much higher performance specifications. This causes the processing chambers 30 to fall out of specifications sooner, which results in shutting down the tool more frequently. Therefore, the downtime associated with calibrating the transport system and repairing/maintaining electrochemical deposition chambers is significantly increasing the cost of operating wet chemical processing tools.